The Obelisk X-2 power supply (in fact, a dual-mono power amp PSU) ups the ante to a full 50wpc, while allowing the original on-board power supply of the Obelisk Si to dedicate itself entirely to its preamp section. In other words, with the addition of this single device, the Obelisk Si evolves into a fully-fledged dual-mono pre/power combination. It is a substantial technical upgrade, and consequently a leap forward in sonic performance: it catapults the single-box integrated Obelisk into a much higher league.